Majdi Abid

Polyesters bearing furan moieties, 2. A detailed investigation of the polytransesterification of difuranic diesters with different diols†

A two-step transesterification procedure was applied to combinations of difuranic diesters and both aliphatic and furanic diols. The reaction parameters (including the nature of the catalyst) were varied in both phases of the process and the results compared with those published for similar systems based on aromatic diesters. The best results related to the first phase of the synthesis were obtained using Zn(AcO) 2 , Pb(AcO) 2 or Ti(OBu) 4 at 200°C with a large excess of diol. The second phase, which led to the actual polymer at 200-240°C, called upon the catalytic action of SnC 2 O 4 , Sb 2 O 3 and Ti(OBu) 4 and was prolonged until the viscosity of the media ceased to increase. Specific problems, related to some fragile moieties, limited the success of these polymerizations to a number of combinations which gave polyesters bearing regular structures and molecular weights in the tens of thousands.

Polyterephthalates Bearing Bio-based Moieties

Dimethyl terephthalate was reacted with 5,5′-Isopropylidene-bis(ethyl 2-furoate), 1,4:3,6-dianhydrohexitols and ethan-1,2-diol in order to obtain PET incorporating bio-based moieties. Polycondensation was achieved in two steps: (i) the formation of a hydroxyethyl-terminated oligomer by reaction of starting diester mixture with excess ED and, (ii) a polycondensation step with elimination of ED was used to obtain high molar mass copolyesters. Copolymers of various compositions were synthesized and characterized by 1H-NMR, SEC, DSC and TGA. The resulting materials are amorphous polymers (T g = 104–127 °C) with good thermal stability.

New Copolyesters Containing Aliphatic and Bio-Based Furanic Units by Bulk Copolycondensation

A straightforward substitution of non-renewable aromatic aliphatic copolyesters by renewable homologous furanic aliphatic copolyesters was successfully realized by copolymerization of furanic unit, aliphatic and 1,3-propanediol. Different copolyesters were synthesized and characterized by 1H-NMR, 13C-NMR, FTIR, DSC and TGA. For all copolyesters, the degree of randomness, determined by 1H-NMR, was close to 1, reflecting a random distribution of furanic and aliphatic ester units in polymer chains. The hydrolytic degradation of polymers was performed at pH 4.35 at 37°C over a period of four weeks. The hydrolytic degradation proved a mass loss of about 10%.

Polyamides incorporating furan moieties 3. Polycondensation of 2-furamide with paraformaldehyde

2-Furamide was treated with an excess of paraformaldehyde in an acidic medium to promote both its oxymethylation and the subsequent polycondensation of the reaction product involving the C5 position of the heterocycle. The molecular weight of ensuing 2,5-furanmethylene polyamide was optimised by examining the role of the synthetic procedure, the catalyst and medium used and the reaction temperature.

One-step Synthesis of PCL-Urethane Networks using a Crosslinking/de-crosslinking Agent

Thermally reversible cross-linked polycaprolactone-urethane (PCL-U) was prepared in one-step procedure. The PCL-U networks were synthesized from a di-isocyanate (4,4′-methylene bis(cyclohexylisocyanate) (HMDI) and hydroxyl bearing macromers and monomers: hydroxy-terminated PCL, glycerol and a di-alcohol Diels-Alder (DA) adduct. This adduct was used to introduce both diene and dienophile functions in the structure and also to protect the maleimide functions from polymerization. The thermoresponsive behavior of the material was characterized by commonly used methods such as solubility tests at different temperatures and differential scanning calorimetry analyses to highlight rDA reactions and also by rheological analysis. The effects of the cooling rate, the molar mass of polycaprolactone as well as the molar ratio [di-Isocyanate]/[PCL-diol] on the cross-linking/de-cross-linking temperatures were also analyzed. The reversible networks obtained have a self-healing behavior.

Polyazomethines Bearing Furan Moieties. Solution Polycondensation of Bis(furanic diamine)s and Aromatic Dialdehydes

A series of new polyazomethines containing furan moieties was synthesized by polycondensation of bifuranic diamine monomers with commercially available aromatic dialdehydes viz., terephthaldehyde (TPA), isophthaldehyde (IPA). Inherent viscosities and number average molecular weights of polyazomethines were in the range 0.90–1.56 dL/g and 10460–17850 (SEC, polystyrene standard), respectively indicating formation of medium to reasonably high molecular weight polymers. The resulting polyazomethines were characterized by solubility tests, viscosity measurements, FTIR, NMR, UV spectroscopy, differential scanning calorimetric (DSC), and thermogravimetric analysis (TGA). These furan-based polyazomethines were essentially amorphous and exhibited glass transition temperatures (Tg) in the 150–190°C range. The temperature at 10% wt loss (T10), determined from TGA of polyazomethines were in the range 300–380°C, indicating their good thermal stability.

Preparation of new poly(ester triazole) and poly(amide triazole) by “click chemistry”

New dialkynyl monomers containing furan and ester or amide units were prepared via three step reactions from ethyl furan-2-carboxylate. Their click polymerization with either poly(ethylene glycol) diazide or poly(tetrahydrofuran) diazide catalyzed by Cu(I) led to corresponding amorphous poly(ester triazole) and poly(amide triazole) with molecular weights in the range of (7–11) × 103 and with glass transition temperatures in the range of −35 and −19°C. The temperature at 5% wt loss (T 10), determined from TGA of polyazomethines were in the range 345–365°C indicating their good thermal stability.

Furanic–Aliphatic Polyesteramides by Bulk Polycondensation Between Furan-Based Diamine, Aliphatic Diester and Diol

In order to prepare furanic–aliphatic polyesteramides without the side reactions taking place with furan-2-carboxylic acids or esters, a furan-based diamine, 5,5′-isopropylidenebis(2-furfurylamine), was reacted in the bulk, either with (i) ethanediol and dimethyl adipate or (ii) with the corresponding aliphatic polyester (polyethylene adipate). The polycondensation involves both amine–ester and hydroxy–ester interchanges, with elimination of excess ethanediol. High-molar-mass furanic–aliphatic polyesteramides were easily obtained. Method (ii) was more efficient than method (i), but no side reactions were observed with both methods. These polyesteramides behave as amorphous random copolymers.

Application of R.O.P. in polymerization of furanic oligoesters with cyclic esters: Synthesis, characterization and degradation

ABSTRACT Furano-Aliphatic copolyesters, such as poly(propylene furanic)-co-(polycaprolactone) (PPF-co-PCL), Poly(propylene furanic)-co-(polylactide) (PPF-co-PLA) and Poly(propylene furanic)-co-(polyglycolide) (PPF-co-PGA) were prepared by ring opening polymerization (R.O.P.) using monomers derived from renewable resources. These copolyesters were characterized by 1H-NMR, DSC and TGA. The degree of randomness determined by 1H-NMR is close to 1, reflecting a random distribution, sometimes less than one. This indicates that these polyesters have a character to block. The hydrolytic degradation of polymers was performed at pH 4.35 at 37°C over a period of four weeks. The oxidative degradation proved a mass loss of about 50%.